The Cancer Center Flow Cytometry Resource exists to provide state-of-the-art instrumentation and expertise for members'needs. This Resource has existed since 1989 and is a highly utilized core at BCM. The Core has a high pressure, high speed sorting instrument and two analytical instruments. Techniques include flow measures of cell cycle, immunofluoresence, functional measurements, and sorting of cells, including stem cells. Dr. Dorothy Lewis, the Resource Director, has more that 25 years of flow experience and has a highly trained staff to meet users'needs. Dr. Lewis also teaches a flow cytometric applications graduate level course, and has open houses to foster information flow about uses of flow cytometry in cancer research. Cancer Center members currently utilize more than 60% of the Core's billable time, studying a variety of cancer biology questions. In 2004-2005, more than 25 publications resulted from the use of the Core. A charge-back system is in place, along with policies and procedures for fair usage and quality control of the instrumentation. The principal use of the proposed Cancer Center budget for this Resource will be to pay for additional personnel to reduce sorting charges to Cancer Center members by 20-30%. The Resource will thus be armed to provide Cancer Center members even better support in the future.